There a number of different designs of 3D display systems. These generally fall into two categories; those that require the user to wear special glasses and those that do not.
3D display technologies which avoid the need for glasses include displays with switchable barrier arrangements, and displays with lenticular arrays. These generate different views in different directions. However, the resolution of the views is greatly reduced if there are many different images projected in different directions, and the position of the viewer is critical in achieving the desired 3D effect.
Systems which require the use of glasses overcome these problems. A viewer can be positioned anywhere within the field of view, and a full resolution image can be presented to each eye in a time sequential manner or else two views can be presented simultaneously with reduced resolution (for example with different polarizations).
For 3D LCD TV applications, the so-called active shutter glasses option has great advantages, as in 2D viewing mode the display system is not compromised in quality, power efficiency and cost. The display does not need to provide special polarizations as in a polarization based system, and full colour 3D can be achieved, unlike systems using colour filtering. Any fast LCD display panel can be used, with only an adapted control method required.
The active shutter design provides sequential images to the left and right eye, and the glasses provide a shutter over one eye to block the wrong image. During addressing of a new field, the shutter glasses can be used to block the light towards both the left and right eyes. To reduce energy wastage, the backlight can be turned off during this period.
In the 3D viewing mode, low brightness is a problem with this design, as the stereoscopic viewing method blocks more then 50% of the light. The implementation requires a relatively small time window when an eye is receiving an image, so that the efficiency of the actual implementation also has losses of about 50%. This reduces light output from the desired 500 Cd/m2 down to 125 Cd/m2.
The invention aims to improve the light transmission of the overall stereoscopic display system. The obvious solution is to provide a brighter backlight, but this results again in high power consumption and low efficiency. There is therefore a need for improved efficiency and brightness by redesigning the optical system.